Abstract: The objective of the present study was to analyze γ-aminobutyric acid (GABA) accumulation associated with postharvest precooling and controlled-atmosphere storage as indicated by GABA metabolism in litchi (Litchi chinensis Sonn. cv. ‘Huaizhi’) fruits. In addition, changes in fruit firmness, color and sensory quality were monitored during storage. The results showed that iced water precooling was better than room precooling for GABA accumulation and storage quality. GABA concentration increased first and then decreased during high-CO2 controlled-atmosphere storage, and the peak concentration (19.97 mmol/kg mf) was 1.4 times as high as that at harvest. There was a positive correlation between GABA concentration and glutamate decarboxylase (GAD) activity, while there was no correlation between GABA concentration and GABA transaminase (GABA-T) activity, indicating that GABA accumulation was mainly due to the enhanced GAD activity, promoting the synthesis of GABA, rather than the decreased GABA-T activity, inhibiting the catabolism of GABA. Pulp firmness, pericarp color and sensory quality of the controlled-atmosphere stored litchi fruits were significantly better than those of the fruits stored under normal atmosphere. Litchi fruits showed serious injury and promptly lost commodity value during excessive CO2 controlled-atmosphere storage.

Key words: litchi, γ-aminobutyric acid, accumulation, controlled-atmosphere storage, precooling